In a conventional art, there have been provided various techniques for easily opening a packaging bag containing powder or liquid, such as by forming a cutout or like to a side edge portion of the packaging bag. However, the formation of such cutout will damage an outer appearance of the packaging bag, and in addition, fear of erroneously opening the packaging bag will also be increased.
In order to eliminate such defect, the inventor of the subject application had already disclosed a packaging bag provided with a rough surface portion at a opening-start point (see Japanese Patent Application No. 2001-140543). Further, it is to be noted that the term of “rough surface portion”, used herein, means a coagulated structure of a plurality fine recesses formed to an outer layer constituting a laminate film and a plurality of fine through holes formed thereto so as to penetrate the outer layer. By providing such rough surface portion to the side edge portion of a packaging container, the strength of such rough surface portion is weakened to thereby easily open the packaging bag from this rough surface portion.
An invention of a packaging bag formed with such rough surface portion is disclosed other than the above patent application (for example, refer to Japanese Patent Unexamined Laid-open Publication No. 2002-211584).
However, in the packaging bag provided with such rough surface portion, there is a fear of slightly deteriorating barrier performance of the packaging bag at that portion in comparison with the other portions. Especially, at a time when the laminate film is pulled, while being drawn by a former of an automatic packaging machine, an excessive force is partially applied to the laminate film, and a portion subjected to surface roughing working, another film portion constituting the laminate film, or aluminium foil will be expanded, thus deteriorating the barrier performance.
In addition, in such packaging bag, particular material, in place of liquid material, may be contained in the packaging bag, and when the particular material is contained in the packaging bag, there is a fear that the particular material clogs a material pouring portion, preventing smooth pouring.